1. Technical Field of the Invention
The present invention relates to cellular communications systems and, in particular, to a multiple hyperband cellular communications system and multiple hyperband capable mobile stations for operation therein.
2. Description of Related Art
North American cellular communications have historically been implemented solely in the 800 MHZ Cellular hyperband. The most recent evolution in cellular communications services involves the adoption of three additional hyperbands for use in handling mobile and personal communications. Of these additional hyperbands, only the Personal Communication Services (PCS) hyperband in the 1900 MHZ frequency range has been completely defined. With the existence of the new PCS hyperband, different types of subscriptions and or services like speech quality, voice privacy, and encryption may exist for one mobile station from one hyperband to another, or from one frequency band in the Cellular hyperband to another frequency band in the PCS hyperband.
The Cellular hyperband is assigned two telephone frequency bands (commonly referred to as the A frequency band and the B frequency band) for carrying and controlling communications. The PCS hyperband, on the other hand, is specified in the United States of America to include six different frequency bands (A, B, C, D, E and F). Thus, in accordance with EIA/TIA Interim Standard IS-136 (the xe2x80x9cIS-136 specificationxe2x80x9d) and the PN3388-1 specification version of Sep. 9, 1994, eight frequency bands are now available in any given service area to facilitate cellular and personal communications services.
Each one of frequency bands specified for the Cellular and PCS hyperbands is allocated a plurality of voice or speech channels and at least one access or control channel. The control channel is used to control or supervise the operation of mobile stations by means of information transmitted to and received from the mobile stations. Such information may include incoming call signals, outgoing call signals, page signals, page response signals, location registration signals, voice channel assignments, maintenance instructions, and cell selection or reselection instructions as a mobile station travels out of the radio coverage of one cell and into the radio coverage of another cell. The voice channel is used to carry subscriber telephonic communications as well as messages requesting mobile station assistance in making hand-off evaluations. The control and voice channels may operate in either an analog mode, a digital mode, or a combination mode.
The individual frequency bands are typically assigned to, and provided within a hyperband for the service area by only one service company. For example, the A frequency band of the Cellular hyperband is usually reserved for use by non-wire line communications service companies, and the B frequency band is usually reserved for use by wire line communications service companies. In some instances, a frequency band assigned to one service company for a given cell or service area may be assigned to a different service company in another cell or service area. It should also be recognized that the same service company may provide cellular communications service in multiple frequency bands within either a single hyperband or across multiple hyperbands.
Cellular hyperband mobile stations have historically been configured to operate in a particular one of the available frequency bands within the Cellular hyperband. For example, if the service company providing cellular service to the subscriber is a wire line company, the Cellular hyperband mobile station is configured with the B frequency band as its xe2x80x9chomexe2x80x9d frequency band. Reciprocal billing arrangements between service companies allow subscribers to place calls over non-home frequency bands in the event the mobile station is roaming. These non-home calls, however, typically require payment by the subscriber of some form of a surcharge and are therefore undesirable. Furthermore, in the absence of an agreement between service companies, roaming subscribers may not be able to make a call in a non-home frequency band without operator assistance. For the service provider, use of non-home frequency bands by subscribers results in a potential loss of revenue that the provider would like to avoid.
The expansion to multiple hyperband communications capabilities as a result of the IS-136/PN3388 specification has necessitated the development and placement into service of mobile stations that are capable of accessing both the Cellular and PCS hyperbands. Furthermore, the existence of multiple available hyperbands for carrying mobile station communications presents an opportunity for cellular telephone switches to control overlapping or adjacent cells in different hyperbands. It would be beneficial if the cellular communications system were configured from both the system and terminal point of view to allow multiple hyperband capable mobile stations to operate seamlessly between the available hyperbands. At the same time, however, some control over which hyperband and frequency band therein that are accessed by the mobile station must be maintained in order to avoid subscriber surcharges and enable service providers to derive revenue from use of their own bands.
The present invention comprises a mobile station capable of accessing for communications multiple frequency bands across multiple available hyperbands. In order to control which of the available hyperbands will be accessed, the mobile station of the present invention is programmed with hyperband and frequency band selection criteria. The programmed selection criteria may either restrict mobile station operation to one or more hyperbands or frequency bands, prefer operation in one or more hyperbands and/or frequency bands, and/or prioritize operation in certain hyperbands or frequency bands. For server selection in the idle operating mode, the mobile station evaluates the neighbor list broadcast by the communications system and, in response to the neighbors identified therein, selects in accordance with programmed selection criteria not only which one or ones of the available hyperbands should be used for mobile station communications, but also which one or ones of the available frequency bands within the selected hyperband should be used for mobile station communications. For hand-off while in the call processing mode, the mobile station transmits the programmed selection criteria at cellular system request for subsequent use by the system in selecting a hyperband and frequency band for communications.
The present invention further comprises a method for operating multiple hyperband capable mobile stations within a multiple hyperband cellular communications system. In accordance with the method, mobile stations are programmed with hyperband and/or frequency band selection criteria. In response to receipt of a neighbor list, the programmed mobile station evaluates the available neighbors on the list in view of its programmed selection criteria, and then selects an appropriate hyperband and/or frequency band in a server selection determination. The mobile station further transmits its programmed selection criteria to the communications system for system use in making hand-off determinations.
The present invention still further comprises a method for operating a multiple hyperband cellular communications system wherein multiple hyperband capable mobile stations are programmed with hyperband and/or frequency band selection criteria. The system generates and transmits to each mobile station a neighbor list identifying available neighbors. In response to receipt of the transmitted neighbor list, the mobile stations evaluate the identified available neighbors in view of their programmed selection criteria, and an appropriate hyperband or frequency band in a serving cell is selected for communications. The system further evaluated mobile station programmed selection criteria received from mobile stations in making hand-off determinations.
The present invention still further comprises a multiple hyperband communications system implementing the foregoing methods of programming mobile stations and using the programming to select appropriate hyperbands or frequency bands in either server selection or hand-off determination.